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The asymptotic winding at a negative puncture is one more than the winding of π∂su\pi\partial_s uπ∂s​u along small circles

Proved
FiniteEnergyPlane.hasWindInfAt_cylEndAt_of_hasLoopWind

by Mazecto · Nov 3, 2026 · Mathlib 0df444a (Lean v4.33.1)

pseudoholomorphic-curvesreeb-dynamicssymplectizationwinding-numbers

Let S=H−1(1)⊂R4S=H^{-1}(1)\subset\mathbb{R}^4S=H−1(1)⊂R4 be a strictly star-shaped level, JJJ a dλ0d\lambda_0dλ0​-compatible complex structure on ξ\xiξ, and J~\tilde JJ~ the induced almost complex structure on R4∖{0}≅R×S\mathbb{R}^4\setminus\{0\}\cong\mathbb{R}\times SR4∖{0}≅R×S. Let U⊂CU\subset\mathbb{C}U⊂C be open and contain the punctured disc B(z0,r)∖{z0}B(z_0,r)\setminus\{z_0\}B(z0​,r)∖{z0​}, r>0r>0r>0, and let uuu be smooth, nonvanishing and J~\tilde JJ~-holomorphic on UUU. Suppose that the ξ\xiξ-component π ∂su\pi\,\partial_s uπ∂s​u, read in Hryniewicz's global frame of ξ\xiξ, has winding number kkk along every counterclockwise circle t↦z0+ρe2πitt\mapsto z_0+\rho e^{2\pi it}t↦z0​+ρe2πit with 0<ρ<r0<\rho<r0<ρ<r. Then at z0z_0z0​ seen as a negative puncture, in the cylindrical coordinates (s,t)↦z0+e−2π(s+it)(s,t)\mapsto z_0+e^{-2\pi(s+it)}(s,t)↦z0​+e−2π(s+it) with ttt traversed backwards (sign −1-1−1),

wind∞(u,z0)=k+1.\mathrm{wind}_\infty(u,z_0)=k+1 .wind∞​(u,z0​)=k+1.

This expresses the asymptotic winding at a negative puncture, which is defined in cylindrical coordinates, through the winding of π∂su\pi\partial_s uπ∂s​u along small counterclockwise circles about z0z_0z0​ in the plane coordinate.

Formalization Note R4\mathbb{R}^4R4 is V 1, J~\tilde JJ~ is Jtilde H J, and π∂su\pi\partial_s uπ∂s​u in the global frame is piDs H u : ℂ → ℂ. The circles are z₀ + ccwLoop ρ t. The conclusion is HasWindInfAt H u (cylEndAt z₀) (-1) (k + 1): for all large sss the loop t↦π∂sw(s,−t)t\mapsto\pi\partial_s w(s,-t)t↦π∂s​w(s,−t) of w=pr∘u∘cylEndAt z0w=\mathrm{pr}\circ u\circ\mathrm{cylEndAt}\,z_0w=pr∘u∘cylEndAtz0​ has winding number k+1k+1k+1. No energy bound or asymptotic hypothesis is assumed.

Preamble
import Definitions.Def_FiniteEnergyPlane_Winding
Formal statement
namespace FiniteEnergyPlane

open MeasureTheory Metric Filter Topology
open scoped ContDiff ENNReal Real

/-- Let `u` be smooth, nonvanishing and `J̃`-holomorphic on an open set `U` containing the punctured
disc `B(z₀, r) \ {z₀}`, and suppose that `π ∂ₛu` (in the global frame, `piDs H u`) has winding
number `k` along every counterclockwise circle `t ↦ z₀ + ρ e^{2πit}` with `0 < ρ < r`. Then the
asymptotic winding of `u` at `z₀`, viewed as a negative puncture in the cylindrical coordinates
`cylEndAt z₀` (sign `-1`), is `k + 1`. -/
theorem hasWindInfAt_cylEndAt_of_hasLoopWind (H : V 1 → ℝ) (hH : IsStrictlyStarShapedLevel H)
    (J : V 1 → V 1 →L[ℝ] V 1) (hJ : IsCompatibleXiStructure H J) (U : Set ℂ) (hU : IsOpen U)
    (u : ℂ → V 1) (hu : ContDiffOn ℝ ∞ u U) (hu0 : ∀ z ∈ U, u z ≠ 0)
    (hhol : JHolomorphic.IsJHolomorphicOn (Jtilde H J) U u) (z₀ : ℂ) (r : ℝ) (hr : 0 < r)
    (hrU : ball z₀ r \ {z₀} ⊆ U) (k : ℤ)
    (hk : ∀ ρ ∈ Set.Ioo 0 r, HasLoopWind (fun t => piDs H u (z₀ + ccwLoop ρ t)) k) :
    HasWindInfAt H u (cylEndAt z₀) (-1) (k + 1) := by
  sorry

end FiniteEnergyPlane
Source
U. Hryniewicz, J. Symplectic Geom. 12 (2014), arXiv:1105.2077, Section 2.2.4 and Lemma 2.15; H. Hofer, K. Wysocki, E. Zehnder, GAFA 5 (1995)

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